The present invention relates to the field of hand-held diagnostic tools used to determine whether humans can distinguish between the sensations of pressure and sharpness.
The device currently used by orthopedists, .neurologists, neurosurgeons, and other physicians to test a patient's ability to feel sharp contact with the skin, and so determine a patient's pain threshold as a test for nerve damage, or nerve dysfunction, consists of a pinwheel rotatably attached to a handle. This device traditionally has metal spokes extending from the hub, each spoke being sharpened on its exposed end to produce a sensation of sharpness or discomfort when rolled over a patient's skin. In the clinical setting, the examiner holds the handle and rolls the pinwheel over the patient's extremity or trunk with the pointed ends of the spokes in contact with the patient's skin while the examiner asks the patient whether the sensation produced is sharp or dull.
All pressure applied by the physician or examiner to the handle is transferred directly to the patient's skin through the pinwheel. As a result it is difficult to control the force applied to the patient's skin or to compare the results of tests performed by more than one physician.
It is almost impossible to effect an accurate diagnosis using this type of pinwheel without the possibility of piercing a patient's skin. Additionally, the same device is routinely used to examine many different patients, and is often not sterilized after each testing procedure. Once it pierces a patient's skin, the spokes of the pinwheel become contaminated by that patient's body fluids and can be a source of cross-contamination. Because of A.I.D.S. and other deadly diseases that can be transmitted through body fluids, both the examiner and other patients tested with the contaminated pinwheel are put at high risk of infection through contact with this type of pinwheel.
Although making the pinwheel's spokes less sharp decreases the chances that they will pierce skin, this also decreases the patient response and thus the accuracy of an examination as the patient senses pressure rather than sharpness. Examination accuracy and safety is further complicated by the fact that skin on different body parts has differing thicknesses and sensitivities; while light pressure may elicit the sensation of sharpness on one part of a patient's body, additional pressure is required on others. Heretofore, the examiner has been solely responsible for providing the proper pressure to elicit a sharp sensation while avoiding piercing a patient's skin.
Besides the possibility of cross-contamination, continued reuse of current devices can result in a dulling of the spokes' points over time, thus reducing the effectiveness of the reusable pinwheel as a diagnostic tool. Additionally, in an attempt to address the contamination issue, some physicians have sterilized the pinwheel devices. Repeated sterilization also contributes to a loss in sharpness.
Physicians have recognized the dangers to their patients and to themselves of using a necessarily sharp and potentially contaminated device for examinations, but have heretofore failed to successfully solve these problems. As an alternative to the traditionally used metal pinwheel, some physicians currently use either a hypodermic needle or a safety pin to test sharpness sensation in patients, since both of these may be disposed of after use. However, hypodermic needles are especially designed to minimize pain on insertion through the skin, and this design is not effective in diagnostic sensation testing. Safety pins are not sterile, and if they pierce the skin can infect the patient. Further, both hypodermic needles and safety pins have only one sharp point, and to test the surface of a patient's skin requires repeated and time consuming poking of the skin in multiple places with varying degrees of pressure to test the patient's ability to sense sharpness.
There is therefore a need to provide a diagnostic device to test a patient's ability to sense sharpness under a more controllable pressure while also protecting both patient and physician from the risk of acquiring communicable diseases through transmission of body fluids.